In general, a drum type washing system performs washing using a frictional force between a rotating drum and washes according to a delivered motor drive force, at a state where a detergent, cleaning water, and washes are engaged in a drum, to thereby cause few damages of washes, and prevent washes from getting tangled, and provide an effect of washing washes by striking and rubbing the washes.
Conventional drum type washing machines are classified into an indirect drive system in which a drive force of a motor is transferred to a drum indirectly through a belt that is wound between a motor pulley and a drum pulley, and a direct drive system in which a shaft that is connected to a rotor of a BLDC (Brushless Direct-Current) motor is connected directly to a drum, so that the motor drive force is immediately transferred to the drum.
Here, the indirect drive system causes an energy loss during a transfer process of a drive force and generates much noise during a transfer process of power. Accordingly, the direct drive system is chiefly applied to the recent drum type washing machines.
Meanwhile, medium-size/small-size drum type washing machines of a wash capacity of 5-8 kg are being installed in a built-in system, in order to enhance an efficient practical use of an indoor residing space in Japan and Europe. In this built-in system, size of a given installation space where a washing machine can be placed is usually established into a space of 600 mm wide×600 mm long×600 mm high. When considering a wash capacity of a medium-size/small-size drum type washing machine, a space (or length) where a drive apparatus can be established from a tub of the drum type washing machine to a rear housing of the drum type washing machine is determined into about 45 mm. In this case, the tub is elastically supported by a spring and a damper in the inside of a housing of a drum type washing machine so as to absorb impact at the time of a forward/backward rotational drive of a basket that is rotatably supported in the inside of the tub. Therefore, in order to prevent the tub from being damaged when the tube moves back and forth, there is a need to secure a clearance space (or length) of about 15-20 mm. Accordingly, a space (or length) where the drive apparatus can be installed is given into 25 mm that is obtained by subtracting 20 mm from 45 mm.
Meanwhile, according to the conventional art, when a direct drive drum type washing machine is implemented in a built-in style by using a drive motor of 63 mm or more thick, a length of a tub should be reduced, and thus a wash capacity of the drum type washing machine should be also unavoidably reduced. Accordingly, the conventional drum type washing machine employs an indirect drive system of a belt-pulley mode in order not to reduce length of the tub, in which a motor is disposed at a lower portion of the drum type washing machine and a basket should be indirectly driven through a belt wound on a pulley. Problems of delivery a driving force and occurrence of noise still exist in the indirect drive system.
In the case of these built-in drum type washing machines, as mentioned above, there is a need to implement a motor of a slim structure due to constraints on an installation space of a drive apparatus. Therefore, it is desperately needed to develop a slim type motor that can satisfy a 25 mm thickness condition that can be employed as a direct drive system in medium-size/small-size built-in style drum type washing machines of a wash capacity of 5-8 kg.
However, since such a slim type motor has a narrow and confined space therein, heat generated by rotation of a rotor and transferred to a stator does not only easily circulate in the inside of the motor, but also is difficult to be dissipated to the outside.
Meanwhile, Korean Patent Laid-open Publication No. 2010-73449 disclosed that a large number of completely split stator cores are integrally molded in an annular form by an annular stator support, and the stator support is extended inwards, and supported to a tub of a washing machine by fastening bolts. However, since the fastening bolts for mounting the stator support to the tub of the washing machine are formed in an inner side of the stator support, in Korean Patent Laid-open Publication No. 2010-73449, there is a limit to have to design the motor considering interference with a leading end of the rotor. Moreover, since the stator is mounted in the tub of the washing machine in advance, and then the rotor is coupled with the stator, a disassembly and reassembly process of the stator and the rotor should be performed even if the stator and the rotor are delivered at a state where the stator and the rotor have been assembled.
In addition, Korean Patent Laid-open Publication No. 2010-73450 and European Patent Publication No. 2,119,819 disclosed that a bearing inserting structure for supporting a rotating shaft is provided for the stator support, and simultaneously the stator is used as a cover to prevent a noise. In the case where the stator is used as the cover, a production cost for the stator rises up and in the case of implementing a slim direct drive device, height of stacking the stator cores increases due to interference of the stator support and thus it is difficult to promote improvement of performance.